Flood Control and Water Conservation District - Regular Meeting

Okay. Good afternoon, everyone. Apologies in advance. My voice is croaky due to a summer cold. And if it gets bad, I have a mask I can put on. But so far, it seems like the meds have got it under control. Okay. So welcome, everyone. And let's start with the roll call.

Member Philip Helle?

Here.

Member Cooper? Present. Member Garcia?

Here.

Chair Kolndorf?

Here. Thank you. Matt, if you want to save your voice, I'm happy to step in. Okay. Would you like me to? That could be helpful. Yeah. Yeah, no worries.

Okay.

All right? Yeah. Okay. Cool. We invite public comments and recommendations. The committee invites comments and recommendations from the public concerning issues relevant to the Church of the Technical Advisory Group. Anyone who wishes to speak to the Technical Advisory Group on such a matter, if it is not on the agenda, may do so at this time. At the discretion of the chair, individuals will be limited to a three-minute presentation. No action will be taken by the Technical Advisory Group as a result of any item presented at this time. Please.

Good afternoon. Peter Nissen, Napa County Farm Bureau. I hope I read over the agenda, and I don't think I'm covering anything in my discussion that is on your agenda today. The first thing I wanted to talk about is the definition of groundwater and well water. And I know that it's gone back and forth a little bit between staff and the Board of Supervisors, and I think that it is eventually going to come to you as about the use of drain water or drain tile water going into sumps and sumps storing that water in reservoirs. From my perspective and the Farm Bureau, it's banking water that would have gone down the river during the winter. And they're using that water during the growing season where they're not using it or drawing out of the aquifer. So it's important that we have a definition and people understand exactly what the well well water and drainage water, if they're one and the same, we need direction on that. Because when you have a sump and you build a reservoir, you don't have to have a permit for a well or anything. So hopefully we can get a situation where we get a definition of that. And if you need any help from Farm Bureau, we're more than happy to assist in giving guidance or getting information from some of our members. Because a large number of people do use Drain water and they've developed reservoirs to store it and use it later when they're not drawing out of the aquifer and hopefully it doesn't create a nuisance with you know, the the water From the surface water against groundwater Second is the removal of vineyards that have been taking place. And I'm just wondering, within the modeling that's taking place right now, we had a meeting with John Tudor at Farm Bureau earlier this year that said over 10% of the vineyards have been removed, and a lot more have been removed since then. And there are a lot of people that are using the method of mothballing. They're using less water. So I'm just wondering if that's been incorporated into the modeling as we move forward and hopefully getting updated information so we have more real numbers until more people use meters and have actual numbers to use. And the last thing I'd like to speak to are the postcards that came out. asking people to reconcile the amount of acres they had. They were irrigating and weren't irrigating. And a lot of people didn't even understand what those postcards were or larger corporations. The representatives never saw them. So if we or other organizations within the industry can help disseminate that information when people can be more precise in exactly how many acres they have under production and they're irrigating, it would be very helpful.

Thank you.

Thank you. Anybody else in the room?

Hi, my name's Ellis. I'm the ecosystem restoration fellow at the Abolitos Foundation, and I'm speaking today on behalf of our founder, Tom Mestera, and the rest of the board. Since 2025, Abolitos has been implementing our pilot process-based restoration project, the Concrete Land Lab, on roughly 70 acres above Lake Hennessey. We've built more than 90 low-tech, hand-built restoration structures made of rock and wood designed to slow water, spread it, and let it sink back into the soil instead of running straight off the hillside. We believe that in addition to increasing groundwater recharge, this approach to ecosystem restoration will have several additional benefits, including improved downstream water quality in Lake Hennessey, enhanced riparian habitats, and reduced bank erosion. Alongside our installations, we've built a robust monitoring system to measure the impact over time, including seven groundwater monitoring wells up to 20 feet deep, soil temperature sensors, sediment aggregation rods, and still in time lapse photo cameras, all in a five-year timeline. We see that as relevant to two things on today's agenda. First, the interconnected surface water and groundwater-dependent ecosystems work plan. The Concrete Land Lab sits on a small tributary system just only about 50 yards from the reservoir, and we're measuring actively how to restore – how a restored hillside changes recharge and channel behavior in these streams. Second, the subbasin periodic evaluation due to the state in January, we'd welcome having our monitoring data considered as a case study of this type of restoration's effect on recharge as an independent multiyear study already in the ground. Abilitos would like to be a resource to this committee and community. We're happy to share our monitoring protocols and data, host site visits for any of you, or provide whatever else could be useful with your work through the GDE work plan and periodic evaluation. Thank you. Thank you for your time.

Thank you. Anybody else in the room? You have anybody online?

We have no callers.

Thank you. We move on to approval of the minutes from our June 11th meeting. I was absent, so I won't be voting for that.

Motion to approve.

Second.

Aye.

Aye. Thank you.

Item number four, reports and comments and announcements.

Thank you, Vice Chair Garcia. Good afternoon. Welcome, everybody. So nice to see the TAG. It's been a little while from the beginning of the summer to the end, but it's nice to have a meeting and particularly see for the TAG anyway a relatively large number of in-room participants. I do have a couple of announcements. First of all, I wanted to thank the Napa Valley Vintners, the Napa grape growers, the Napa Wine Growers Association and others for inviting myself and Brendan McGovern to your Local Leaders Tour that was held on August 27th. It was almost an all-day event. It looked like about, gosh, 60 or so people. Really great opportunity to collaborate, learn from each other. We had presentations from a very prominent vineyard management company, from other growers, wine makers, and market experts, and it was just a really valuable experience that we appreciated being part of. So thank you for extending that invitation. Second announcement, kind of a big thing, one of our public members alluded to this, our groundwater fee, which has been a long time in the making was, well, it was adopted in December of last year, but the final kind of cherry on top, if you will, is that the GSA had noted that in their June budget hearings, June of 2026, they would consider whether and how much money they might provide additionally to offset the cost of those fees. And they did. They allocated an additional $750,000 from the fund balance from the previous year, which effectively dropped the rates about 55% for all three user classes, both ag, public water systems, and self-supplied users. The final levy roll and the revised rates were approved by the GSA on August 11th, which was kind of the final procedural step necessary to get those onto actual property tax bills, which are going out, should be in the next couple weeks. with the first bill being due in December. And again, alluding to the postcard effort, we mailed postcards to several, I think it was about 2,600 folks in those three user classes, informing them of this fee. And of course, we had worked for years preceding that with the grower groups, specifically kind of bringing them along in the process of what was happening. But that was our direct outreach piece of like, hey, this fee is happening. It's coming. We had two public workshops, virtual workshops to help inform people. I certainly hear the message that, you know, I know that there are people who didn't receive that. And that's unfortunate. But it was a huge effort, and I really want to thank RCD staff and our tag member, Miguel Garcia, and his colleague, Francisco Larios, and also my own staff, Nick Featherston and Brendan McGovern. as a result of that postcard my staff fielded over a thousand emails um 160 phone calls representing this is to me the most meaningful number about 10 000 acres in the napa valley sub basin with questions about the fee and not just you know superficial easily questions frankly they were really tricky and Nick and Brendan did a huge amount of work to help growers in particular really dig into their alternative water use and other things to help people get the base rate wherever possible. And again, thank you to Miguel and Francisco as well. They did over a, forget how many, you probably know how many dry farm verifications, you probably know how many dry farm verifications it was.

It was mainly Francisco. I cannot.

Okay. It was mainly Francisco, but it was over 100 hours. And we really didn't know kind of what level of effort this might take. And frankly, we're pleasantly surprised, but it just felt like just every other day we were calling them up and saying, okay, we've got more and more and more for you to do. So I really want to acknowledge their efforts. It was huge. And we expect it will be much simpler for everybody involved next year. A couple other quick updates, and I'd also like to get updates from the TAG members, so I'll give you an opportunity there. We are still working on the certification pilot program, awaiting, we put out a memorandum of understanding, a draft for comments from a couple of the interested CERT programs, so we're awaiting comments there to hammer out the kind of final details. And we are also pursuing a five-year recharge permit from Department of Water Resources to hopefully allow us to do a pretty comprehensive groundwater recharge program. So on the supply augmentation side, we've talked a lot about demand management, but we don't want to ignore or neglect the other side of the equation. So we will report back on that as we progress through the process.

I have a quick question about that. So if we're out in the community, say, talking to people who may be interested in that, is there any way for them to show that interest to you? What would be the process?

at the process at this point would be to communicate to let you or any or any of our other tag members or members of the community who are interested you can contact us directly jameson.crosby countyofnapa.org or groundwater at countyofnapa.org but there's no like guidelines at this point as far as what people might be signing up for or what you might need or And might there be like a one pager or something that would be easy for us to there will be yes Absolutely, and we'll want to enlist your help and the help of some of the folks I appreciate Peter Nissen's comments and offer of support from the Farm Bureau we will definitely be reaching out to you and the grape growers and others with some, yeah, very simple guidelines to start with just to kind of elicit interest. But we don't have a lot just yet, but we'll put something together that you all can disseminate. Okay.

When might we expect that? Sorry. Accountability.

Fairly soon. I couldn't tell you exactly, but pretty soon. Pretty soon. Okay. Yeah. Yeah. And your question is good because it's just a prompt of another thing that needs to get moved to the front of the stove. So with that, yeah, I'll turn to any of the tag members if they have reports or announcements of their own.

Okay.

Any interesting harvest stories to date? Not to put you on the spot. No. Okay.

All right. So now we're moving into item 5A. We're going to get an update on the interconnect surface waters, groundwater-dependent ecosystems, work plan implementation, and the California Environmental Flows Framework Assessment. Thank you.

All right, good afternoon. It's been a long summer since we last spoke. And you heard about all the things we were doing to put SEF together, to put our analysis together. And so we're going to today present some of the work we've been doing to sort of provide a basis for the sustainable management criteria, at least from an ecosystem perspective. And then Vicki will be talking a little bit more about this in the next section. So just to remind you, because it's in our contract that we have to show this slide every time I present, that we're implementing the California Environmental Flows Framework, the first two sections, which are the science-based sections. And the Environmental Flows Framework, or CEF, is a systematic framework. to use functional flows to develop scientifically defensible environmental flow recommendations throughout California. SEF identifies the different functional flows, which range from wet season base flow, peak flows, spring recessions, and dry season low flows. And our focus is on the spring recession flows and dry season low flows, because that's when groundwater can have an effect. And the way we're using CEF to develop surface water, we're using the CEF to develop surface water depletion sustainable management criteria. And we're using the biological and habitat mapping that's occurred since 2024. which includes species utilization by life stage, habitat conditions, stream temperature, and dissolved oxygen, and also hydrologic monitoring and modeling, including shallow groundwater, stream flow, and wet-dry mapping. And together, we'll put those two together to identify limiting factors, and then determining flow requirements and allow, based on those flow requirements, help to set the depletion that won't impact... So this slide we've seen before, this is just to remind you of the process and timing. We implemented the work plan starting in 2024. There's been modeling and monitoring ongoing, including biological hydrology. And then there's the models being currently updated. We're using that to develop CEFs section A and B, including ecological goals and flow requirements. And those CEFs section A and B, the report is going to, a draft report is going to come out in October, and it's going to be included as an appendix to the periodic evaluation, which is due at the end of January in 2027. We'll also, in 2027, embark on this CEF Section C, which is where all the different water users come together to develop, to take those environmental flow requirements and other water requirements in the basin to try and come up with a plan. And this is the other contractually obligated picture. This is just to remind us that the subbasin and the watershed are different, that the watershed includes a lot of areas upstream of the subbasin. And upstream of the subbasin, the The tributaries tend to be perennial in their lower reaches, have cooler water and better habitat. And within the subbasin, you have a mixture of intermittent and perennial streams. The water temperatures tend to be higher, and there's widespread incision that happened on the main stem Napa River. And one other point here is that downstream of the sub-basin is the Napa-Sonoma Marsh area, which can have Jacob Katz, I think, spoke to us about a year ago about this, about the extensive rearing habitat that is available down there. So there's a lot of habitat upstream of the basin and downstream as well. So continuing just sort of some background information, So these are maps we worked with Napa County and the RCD to identify reaches for a stream watch. We took some data that Nick Featherston pulled together. And here we're just showing three snapshots where the green is flowing conditions, the red is dry, and blue is isolated pools. And you can see if you come out, 2025 In downtown Napa, it was a slightly dry year. But for the upper part of the basin, it was actually quite wet. And so in May 2025, the tributaries and main stem were flowing based on stream watch data. But once you come out to July, a lot of the tributaries start to become dry or moving to isolated pools. And then by September, The main stem moves to isolated pools in a lot of places. And the tributaries also continue to be dry. And so what this is telling us is that if something's moving in and out through the basin, it starts getting harder in July. If you've got fish that need to get from Sulphur Creek down once the bottom base of Sulphur Creek starts to dry up, they're not going to have much success. So July becomes a key time period for us. And then this is an illustrative plot just showing the amount of surface water depletion that was calculated using the model between 1988 and 2022 for dry, normal, and wet years. The first thing that stands out is that it looks like someone didn't make any calculations for Sulphur Creek and Bale Slough, but put them on the figure anyway. But there actually are calculations there. It's just that those sites aren't depleted by ground. There's no surface water depletion. In the case of Sulphur Creek, because it's The base of the channel is always above the groundwater level. And Bale Slough, the base of the channel, is only below the groundwater level at the height of winter. But there is depletion in the main stem, which is the top four graphs. And that depletion increases, is low in the spring, and then sort of increases as you go through the summer, and then declines again in the fall. And then this is another, gosh, this just shows the six sites that we've been doing intensive studies at, which is four main stem sites and two tributaries, Sulphur Creek and Bale Slough. And then I've talked to you a lot about the different measurements we're taking. But they range from shallow groundwater elevation and monthly wet-dry mapping over about a mile-long reach. The RCD, which is done by the RCD, RCD also mapped fish habitat once at each site, mapped fish occurrence each year using snorkel surveys. We've been monitoring stream temperature and dissolved oxygen at these sites. done foothill yellow-legged frog surveys and environmental DNA to test for their presence, and the same with Northwest pond turtle. We've mapped vegetation and vegetation stress and did California freshwater shrimp surveys in the Napa River at Calistoga, which is the only place which is within their critical habitat. So we did this analysis for different species. The two that get the most focus in the CEF report are steelhead and foothill yellow-legged frogs. Today, I'm just going to talk about steelhead, because the timing of use ends up being about the same. Foothill yellow-legged frogs emerge or metamorphose from tadpoles in June, is what we've observed so far. And the flow requirements for steelhead tend to be higher than foothill yellow-legged frogs. So we're going to just talk about steelhead today. But the CEPH report does go into both. And this slide is to sort of talk about the different life stages and the timing of steelhead. Steelhead are unique among salmon in that they can spawn, and then they don't die. They can swim out to the ocean again, and those are called kelts that do that. That migration happens in the winter through the spring. Juvenile rearing happens year round. The juvenile steelhead have to stay in the watershed for a year or two before going out in the watershed or the marshes. And out migration tends to happen in the spring through about June. It shuts down. But there's also intrabasin movement that happens, which is juvenile fish going from places with terrible habitat and going to places where it's better. And this has been documented in a lot of different places and accounts for some of the small numbers of fish we've seen, which are probably just moving from place to place. And just to remind us that during the dry season, there are stressful temperatures and dissolved oxygen levels within the main stem Napa River. So we put those surveys together and came up with different limiting factors at each site. And for most of the sites, we don't really know much about connectivity and when the channel becomes impassable for the fish, except maybe at Sulphur Creek, we have a little bit more information. The limiting factors are Calistoga has does go dry, has stressful stream temperatures and dissolved oxygen. But there might be a little bit more refuge there because you're closer to the hill slopes and the better habitat. And Calistoga itself has a little bit better physical habitat than the other sites, where the other sites have pretty terrible physical habitat, meaning there's not a lot of bars and pools. But the other main stem sites all have stressful stream temperatures. The Napa at St. Helena goes dry every year, or most years, and stressful dissolved oxygen. There are fewer limiting factors in Sulphur Creek, which seems to have generally better habitat conditions. And if you look at what we've seen during the the snorkel surveys for fish, we see a lot more fish in Sulphur Creek than we do anywhere else. The two places with the most fish are Calistoga, which we only saw in 2024. We saw a lot of juvenile steelhead. And then in 2025, we mostly saw Chinook salmon. And then Sulphur Creek, we saw just a ton of steelhead in 2025, which was a slightly wetter year. But the other sites, we see a few fish. We saw 12 adults at Yonville in 2025, a couple of adults at Oak Knoll. Those are probably fish just moving around the basin. And then juveniles elsewhere. So this is just taking the figure that I showed at the beginning at the life cycle, showing the different timing for killed out migration, juvenile rearing, and juvenile out migration, and interbasin movement. That's the upper figure. The spring recession period is indicated in green, and dry season base flow is in yellow. That's sort of the average timing, the range of times for those. And different water year type, the range of flows measured at St. Helena. So we have the range of flows as shown in the blue shaded area. The lighter blue is 10th to 90th percentile. So it shows you kind of the range. Also, this figure says that St. Helena goes dry over 25% of the time starting in mid-July. And then we're going to go step forward. And the solid line is what we saw in the year 2025. These are the model results for that same period. Note that the axis here goes below 1 CFS, where the model is probably not super accurate. But it shows the... the what we saw, what was observed in 2025, and also sort of a baseline median value. And you can see that depletion, this just shows the same thing that we showed on the average conditions, which is that depletion tends to mostly be focused in the June through October period, and that the June through October period is mostly what we want to say here. So that's when depletion occurs. And yeah, ignore anything above below 1 CFS on that plot. Here we have stream watch data from 2025 on the bottom, where blue is flowing and orange is isolated pool. Yellowish orange is isolated pools. And then our wet dry mapping that was done in the field over a mile long reach by the RCD. And you can see that the channel starts to go dry during dry season base flow. And by August and September, more than half the channel is dry. And then adding other limiting factors here, we can see water temperatures with the orange and blue being two different temperature gauges, one at the upstream of the St. Helena reach and one about a mile downstream. And that dashed line on the middle plot there indicates 25 degrees C, which is the point at which fish really start to struggle and survival is decreased. And you can see that we have periods of weeks in July and August where that stream temperature is exceeded at that upper temperature site almost every day. The plot below shows dissolved oxygen, where you don't want to be below that dashed line. So if you get below 4 milligrams per liter of dissolved oxygen in water, then that also starts to impair fish health. And you can see that by August, we've reached a point where the dissolved oxygen conditions are too low. And this was during 2025, which was a relatively wet and relatively cool summer. So almost ideal conditions. So taking all that stuff together and things that we know about fish elsewhere, first we know that juveniles tend to migrate to areas with better habitat conditions. It's been documented in a lot of studies. Northern California coastal streams. Interbasin movement likely continues until the tributaries transition to isolated pools and connectivity decreases. And stream temperatures and dissolved oxygen concentrations decline during the summer and are stressful for steelheads. So they're going to want to get out of these sites that we've been looking at. So then we started thinking about, well, so how can we get a number out of that? At what point does flow become too low for steelhead to move? And so we can use the literature to define some depth thresholds over riffle crests. Riffles are just the shallow areas of the river. And from the literature, when the depth is less than about 0.7 feet, adult steelhead tend to not migrate. Juveniles that are over a year old need about 0.4 feet of depth, and young of the year need about 0.3 feet. If the depths are less than that, they don't move, and then they'll get stuck and die. So what we really want to create for each site is a chart that looks like this, that has flow on the x-axis and understanding the critical riffle depth. Actually, what we want to understand is depth and how that changes through time to identify these three different critical riffle depths for young of the year, juveniles, and adults. with the young of the year focus occurring over summer, whereas the juveniles tend to stop migrating around May, based on the rotary screw trap data the RCD has been collecting. So thankfully, when the RCD did habitat mapping at these six sites, they defined what the average riffle depth was. So we can use that as a starting point. It's one data point, which is not a lot, but it's one data point. One data point isn't enough to make a line, but it's better than zero data points. And so here we're just showing at each site during those surveys, which happened in June and July, what the depth was. And you can see that in Yountville and Oak Knoll, the depths were larger than in St. Helena and Calistoga. And so we've got two places where we have both depth information and discharge information. And that's St. Helena and Calistoga. and that is they're both at the two gauges. And so the St. Helena, the average depth over riffles was about 0.2 feet, and that was when the discharge was 2.2. eight cfs uh which is not a lot of flow and that 0.2 feet is probably is not enough for for juvenile steelhead so when that survey was done in uh late on six on june 28th the day before my daughter's birthday uh the steelhead any steelhead that were in there are trapped they can't they aren't going to be able to get upstream or downstream um and you need more flow so So then I did a calculation that I 100% know is wrong. I know this number is not correct, but it's a straw man for us to start with. So what we used was the stage discharge relationship of the gauge to think about, well, how much more flow would you need at the gauge location to increase depth by that amount? I'm certain that's not 100% correct, but it's a good starting point for us. And it turns out that you only need to increase flows a little bit to get up to that 0.3 feet, so something like 3 CFS. And to get up to 0.4 feet would be 3.4 CFS, and then 0.7 feet would theoretically occur at 4.5 CFS. These are very preliminary numbers that need to be validated, which we're going to do next June. If we move to Oak Knoll, when they did the surveys, the surveys were done in July 1st at Oak Knoll. And at Oak Knoll, they had a flow of about 10.5 CFS. The critical riffle depth was 0.5 feet. So that means that both young of the year and juveniles would be able to move there. through that system and if we do the same thing we did at the previous site in reverse we get a critical flow of about 6.8 cfs for 0.4 feet and about 4 cfs for 0.3 feet and the adults need more flow at about 20 cfs again that's those are data with very large caveats so good news at oak knoll you can still move through there's more water moving through that system than upstream at saint helena So how can we make those numbers more robust? The way to do that is to develop staged discharge relationships at critical riffles of the sites of interest to refine these sustainable management criteria, or at least to refine the ecological needs there. We can go out next May or June, depending on whether this promised El Nino comes to pass, and go out and measure the riffle depth something like weekly and get a pretty good estimate of what the flow depth is. And this number would be a little more robust, actually, because you don't need to have the average riffle depth. be that deep. You just need to have it the minimum depth to exceed that over a certain width so the fish can get through. And so we recommend doing that next year to refine these requirements and to continue to monitor both the flow connectivity that the ARCD has been monitoring monthly to better understand how much of the reach is wet at different times of the summer, and also to continue measuring stream temperature and dissolved oxygen, which is very useful for us to know how that varies from year to year. And also, as the work plan calls for, continue to monitor fish usage at relevant sites to get to better understand how that varies from year to year through 2028, at least. Okay, so in the summary for my section of the presentations you're going to hear today, Section A and B of the CEF was applied to the subbasin to inform sustainable management criteria for interconnected surface water with a focus on steelhead, at least what I've presented today. Stream temperature and dissolved oxygen are too stressful for juvenile steelhead rearing in the main stem, and tributaries become disconnected in July on average. So that means most of the fish that you're going to see coming through are coming through from tributaries into the main stem. So once those tributaries become disconnected, you're going to have fewer fish moving through the system. Sustaining populations of steelhead require supporting juvenile steelhead out migration and intrabasin movement through at least June. And stage discharge relationships associated with minimum depths for juvenile passage can be used to determine minimum thresholds. And then we'll continue to do surveys in 2027 to better understand links between groundwater elevation, discharge, and flow depth at riffles to complement stream temperature and dissolve oxygen monitoring. And that is the end of my presentation.

Thank you, Christian. Appreciate it. Thank you. Any questions or comments from the tag?

couple of clarification points for your calculation which you say is for sure wrong yes the best calculations how did you how did you do that look but there is the beginning at least of stage discharge relations

There is a stage discharge relationship at the gauge location. But that stage discharge relationship is not necessarily at a riffle. So often the stage is measured at a pool. And the width might change between that pool. And the velocity certainly could change. And the width could also change between that pool and the riffle. So we know it will be a little bit different. at the riffles at riffles especially as you start to get first if you might have the riffle of interest might be you know a half mile downstream from where the the gauges so It's a first cut like it's it's it's I don't want to say it's a bad hypothesis, but it's a it's a It's a first guess that we can then test and we can then test with with actual field data next year and

I was just curious how you made the estimate.

Oh, I just downloaded the stage and discharge data and looked at what discharge the stage had increased relative to our riffle depth sufficiently.

OK, so where you had riffle depths, and then you compared that with the stage behavior.

Yeah.

All right. And streamflow depletion, is that from the hydrologic model? yes as the only way you can calculate it yeah okay so it's it's not a real-time thing necessarily i'm curious what what's your assessment of um of how you know the model's kind of on a big scale and and we're here we're looking at a more focused area what's your sense of uh of how good that number is going to be for this particular purpose? And are there ways that we could improve that?

Well, at these sites, we have a lot of information. that we can calibrate the model to. We have streamflow from the USGS gauges, and then now these new CalSIP gauges that I think you've heard about that were installed that are operational as of July. Yeah, installed in mid-July. So we have more places where we'll be able to do that. And you also have shallow groundwater well data there. So there's a lot of things to calibrate the model with. I think I deferred to Vicky about how accurate it is. But it's probably not accurate to one CFS. But it is. I don't know what that threshold is, but you can also use the wet-dry mapping. It can be a good test, too, to see how well it's doing. It's a lot to ask of a model to do. streamflow as well using the preponderance of evidence with the many different sources yeah we have a lot of data to test it with and and uh the the legal regulations say the that that of Sigma say you you know one of the things you have to do is streamflow depletion and We keep waiting for the finalized guidance of how to measure that to come out from DWR. It hasn't come out quite yet. It was supposed to come out last fall. And I think before that, I mean, I feel like it's been this moving target that makes me feel good about how I deal with deadlines. The fundamental problem from an ecological point of view of it is that fish and frogs and shrimp don't care about stream depletion. They care about whether or not there's enough flow for them to do the things they need to do. And so the trick is going to be, and Vicki's going to talk a little bit about this later, the trick is going from that information that about what the biology needs to how to translate that into streamflow depletion. And I think it's going to be a, you know, the thing I always remind myself about SGMA is that it's not, the desire is not to get an answer for right now. I mean, we're trying to develop this over, we've got a long time to get this right. And we obviously want to do it so that we're not having severe impacts that we can't recover from right now. But it's designed so that you're constantly re-evaluating the numbers and getting it more accurate through time.

We're still doing a lot of this on the main stem when the fish surveys indicate that the tributaries may be important habitat as well. So how do we move some of that?

I think the thing with the tributaries is that because they're up on the alluvial fans, they're just not affected by groundwater pumping in the same way the main stem is. I mean, the main stem is very incised, and it sets the base level for groundwater in the basin. And so the modeling shows and the monitoring that we've done, the one I'm most familiar with, we have the longest record for is Sulphur Creek now for a few years. The groundwater just isn't shallow enough ever to, like you can't use groundwater management to improve flows there. It's much more dependent on what's coming in from upstream. So the... Things like flow diversions outside of the groundwater basin are probably much more important for Sulphur Creek than groundwater management is. And we're trying to, I think what the thinking about in terms of fish passage is our way of saying the tributaries are important where all the fish are. And those tributaries dry up, so those fish need to move either upstream or downstream. And if you're a little baby fish, it's easier to swim with the current than against the current. So we've been sort of focusing on getting them, Our focus is how can we support the rearing that's occurring in the tributaries where there's control of flow due to groundwater. And so that's why we've gotten to this fish passage thing. Yeah.

It just does my brain in a little bit. it's an ecosystem right but then we're sort of trying to model and manipulate one aspect of it without being able to really necessarily look at all the pieces holistically I guess.

Yeah. I mean, there's 100% that. I don't disagree with that at all.

Yeah. So that, yeah.

I mean, I do think the RCD is doing a lot of work. The RCD isn't just doing work in the groundwater basin. They're doing work throughout the watershed. And so... I think that we do have a better understanding of where a lot of fish are. It's just that our study that's been focused on groundwater hasn't gone to those places where the habitat is better.

Anything else from the tag? Any comments from the public in relation to this presentation?

Good.

Hi. My name is Chris Malin. I'm the Executive Director of the Institute for Conservation Advocacy Research and Education. Thank you so much for your SEF presentation. I did want to ask if you could Could he clarify where his data came from regarding to the riffle depth requirement minimum threshold for adult, juvenile, and young of the year? I'd be very interested to know.

Maybe you said it and I missed it.

Yeah, I'd like to know where that came from. And I would like to just emphasize that is minimum threshold, because if you visualize a steelhead adult like this, probably about that big, and it's going to get 0.7 inches of water. Is that right? Am I saying that? Oh, feet. 0.7 feet. Okay. Much better.

That would give them plenty of room to move, I think.

Yeah. Thank you for interrupting me and clarifying that. Then I do agree with Monica that we're taking a snapshot approach to what's going on in the watershed at the sites that we studied that we figured had ecological resources worth protecting. But ICARE has done snorkel surveys for 26 years in the Napa River. watershed in particular one sub watershed and the fish go where the water is where the water quality is and luckily they're still niches of ecosystem left in the watershed where they can hold up, and they hold up high, high, high in the watershed, at least steelhead do, which is what you're studying. And we're finding a sustainable population up there. Dr. Charlie Dewberry is our scientist, and he does a yearly report on that. They're definitely under stress and the numbers are down, but it's still a sustainable population high up in the watershed. But that's the last place. That's the last remaining place in the watershed where we... Sorry about that. where we have steelhead. And much of the rest of the habitat is diminished because of little to no flows. And on the way to no flows, you get terrible water quality. So you get, as you've learned from his presentation, But I'd also like to highlight that it puts the public in danger because we get those terrible harmful algal blooms. And right now, Bell Canyon is being listed at the California Water Quality Council as caution for harmful algal blooms. You can go on that website. You can see everywhere in the state where those are occurring. So we really have to pay attention to flows.

Thank you. Any other comments from the room?

Peter Nissen again. I have a question about, you talked about diversions would offset the flow at Sulphur Creek as opposed to, let's say, pumping groundwater. Are those diversions people using riparian water rights? And I'm just curious how often you come in contact with people that are using their riparian water rights on the stream stem or the main stem of the Napa River.

I don't actually know. I know that there's been a lot of work by the water board to better understand what the diversions are. And I was just talking about, for Sulphur Creek, I was thinking about how to manage it in the future. If you were worried about maintaining flows, the thing you would target is not so much groundwater as increased surface water diversions.

Thank you. Any other comments from the room? Anyone online?

We have one caller. David, you will have three minutes.

I hope you can hear me.

Yep, we can hear you.

Good. Thank you. I apologize for having done a document dump on the group. But I've spent a great deal of time trying to do a good job for our charismatic macrofauna, the steelhead. Our watershed is one of the most important in the whole San Francisco Bay system. I think the SGMA process has turned our gaze away from the really high quality habitat. Um, and toward the, um, the warmer, um, less oxygenated, less preferred by steelhead, uh, habitat. I appreciate, uh, Christian Broderick's analysis. I just wanted to put the amount of water in context. A cubic foot per second over the course of a year is, uh, 725 acre feet, more or less. Now, obviously we don't really care about acre feet in January, but there is kind of a zero sum aspect of where did that water come from to do that. In my more lengthy comments, I did suggest that perhaps thinking about shifting the time of diversion into higher flow parts of the year would enable us to stop pumping in times of year when our groundwater, use of groundwater resource stresses the ecosystems, groundwater-dependent ecosystems especially. So I think that we haven't thought creatively enough about ways to address the issue. We don't really understand enough about how we might do managed stock for recharge. So the devil's in the details. I think we're partway there, but we need to look with a bigger lens, with more expertise, and with understanding the importance of this population of steelhead, which is amongst the most important for a very long stretch of California. Thank you.

Thank you, Dave. Appreciate it. Anybody else?

We have no other callers.

Thank you. We move on to Item 5B. We're going to get an update on the Napa Valley Subbasin Periodic Evaluation. This is required to be submitted by the Napa County Groundwater Stabilization Agency to the California Pound of Water Resources by January 31, 2027. Thank you.

Thank you, and good afternoon. I'm Vicki Kretzinger-Graeber with Ludorf & Scalmanini Consulting Engineers. And my colleague, Erica Sanborn, is here with me today, and Nick Watterson. And we're going to touch on the periodic evaluation, amongst other things that are part of that evaluation. So I'm going to provide a brief overview of what that's about and what you'll be receiving in draft form in October for review and then comment. It is due at the end of January, as Christian mentioned. But key parts of that include groundwater conditions that Eric is going to talk about and also an assessment of the monitoring network. and refinement of sustainable management criteria. And we're going to focus on two sustainability indicators in particular, the reduction of groundwater and storage and interconnected surface water. So the periodic evaluation, this is something that has in the past sometimes had other ways of being described. And the Department of Water Resources is very keen on using specifically this terminology, the periodic evaluation. It is not a GSP plan amendment. It is not a GSP update. It is more of an evaluation of how GSP implementation is going along, including the monitoring network and whether or not the monitoring network is achieving the intended objectives, and looking at the sustainable management criteria and how the monitoring network results are addressing the criteria that have been established. and projects and management actions and what's been implemented and how that's going. So we're going to cover a few of these items today, and it's kind of a sneak preview to what there's a whole lot more information about inside of the periodic evaluation itself. So one of the things that occurred when DWR sent a letter of approval of the GSP, Groundwork Sustainability Plan, submitted in January 2022, when DWR came out with its letter, it's referred to as a determination letter, it also had a few corrective actions in it. And we've touched on this some years ago when the letter was first received. But we wanted to revisit these. So two of them actually involve some recommendations related to definitions of the sustainable management criteria. One is related to removing drought year conditions for the chronic lowering of groundwater levels, sustainability indicator. That's something that we had actually removed a lot of in other criteria, but this is one that we will now remove in this particular sustainability indicator. Another recommendation that the department had was to include a metric, a minimum threshold for a longer period of land subsidence, not just year to year, but looking at a cumulative effect. And so we've included that in the annual report that we've provided to this group and submitted to DWR by April 1st. So this is another definition that we have already implemented. And the other corrective actions were a three-part one in relation to interconnected surface water. As Christian mentioned, one of the recommendations was to utilize the guidance that DWR is still in the process of developing on the refinement of minimum thresholds, measurable objectives, and management actions. This is a third, I believe. There's a collection of guidance documents, technical memorandums that the department has developed. The other two were more about examples of what's gone on. In the Napa Valley sub-basin, it was one of the very few sub-basins that actually developed a stream depletion volume over a specific period of time to meet the requirements of the GSP regulations. Most other basins or sub-basins use the sustainable management criteria for groundwater levels as a proxy for streamflow depletion. Another thing that the department had recommended was to continue to fill data gaps and collect additional monitoring data. in order to aid the management of depletions of interconnected surface water. And as the TAG has heard on several occasions, there's been quite a bit on that front to install 18 new monitoring wells and develop the interconnected surface water and GDE's work plan. There are now the five CALSET gauges that have been installed and the rating curves will be developed soon. And then there are the RCD stream reach surveys and a lot of other additional monitoring that is atypical for most basins that involves aquatic and terrestrial GDEs. The other thing that the department commented on was to collaborate and coordinate with local, state, federal agencies and others to help understand the potential impact of pumping on interconnected surface water depletions. This has been occurring in coordination with the State Water Board on the model that they've been working on for the Napa River watershed with DWR. As Jameson mentioned, we've had some conversations with DWR about technical support services for implementing recharge, a five-year temporary permit for recharge within the sub-basin. And then other conversations with the California Environmental Flows Group about the implementation of the California Environmental Flows Framework, and also with the Nature Conservancy and others who have been involved since the onset of California Environmental Flows Framework. So as we go forward here with various parts of the presentation, Erica is going to present an overview on groundwater conditions, followed by a TAG discussion of that piece. And then Erica is going to describe the assessment of the monitoring networks that we've been doing. That'll be followed again by some more tag discussion and questions. Then we'll take a short break before we turn to the discussion of the refinement of sustainable management criteria. And one other thing about the periodic evaluation This is involving a lot of different contributions from a lot of different corners. So it's our firm, Ludorff & Scalmanini, but it's also Stillwater Sciences, it's ERA Economics, it's the county, it's the RCD, it's David's Engineering, and directly for the work that they're doing on the CalSIP stream gauges. So there's a lot of information that's all being rolled into one document. that will be a very comprehensive discussion of where we've come to date in the five years since the GSP was submitted. And I'm going to pass this to Erica so she can give you an update.

hi everyone all right um so yeah um the yeah so one of the main pieces of the periodic evaluation is evaluating groundwater conditions over the evaluation period which is generally um in our case 2021 through 2025 so five years But we also have kind of additionally evaluated some, like, extra context, such as using spring 2026 data, which I'll talk about a little bit, and then also some, like, longer-term evaluations, just to get, like, a broader picture. in a more complete evaluation. So the evaluations examine groundwater conditions relative to sustainable management criteria. And in the case of this first sustainability indicator, chronic lowering of groundwater levels, that's defined as the minimum threshold is defined as the fall groundwater level or October groundwater level at each representative well. And then the undesirable result would occur if there were 20% exceedances. So of the representative wells, if 20% of them had measurements that exceeded the minimum threshold, there would be an undesirable result. And as mentioned, we removed the non-drought year condition from that definition. So for the groundwater level network, about half of the sites are representative. And so those are the pink locations on the map. And then... Uh, oh yeah. And then I wanted to mention that the, uh, Northeast Napa management area has some distinct groundwater behavior, um, conditions that go along with the, the geology of the area. So there's sort of a separate evaluation, um, exclusive to that area. And then also the sub basin as a whole. So here is a look at some results from this evaluation. So we have, you could think of it as red is bad, green is good. But this is a histogram where the bins are representing wells and how the fall groundwater levels measured each year. related to the sustainable management criteria. So was it below or sorry, was it did it exceed the MT? Was it close to the MT? Was it kind of in the middle? Was it close to the measurable objective, which is good? Or was it even better? Was it above the measurable objective, which would be that dark green? So just at a glance, you can see that from the left in 2021 all the way to the right in 2025, we have this general improvement on that top row there, which is the... non-northeast Napa management area, the rest of the Napa Valley subbasin wells, where we had a relatively high number of MT exceedances in the first two years when the conditions were really dry, but that that fixed you know like things things got better with the wet year in 2023 and continued to stay pretty good um however if you look at that second row um that's the northeast napa management area wells it is a low end it's only six wells but um you can see that as we move through the evaluation period Not too much improvement. I wouldn't say things got worse, but it's not what we're seeing in the rest of the subbasin.

Quick question. Is this calendar year or water year?

Yes. So the fall water level measurements are not always taken at the same exact time every year, and the water year technically ends you know, September 30th. So a lot of the measurements were like October or November, um, in 2025, for example. So technically 2026 water year, but they were used in the 2025 analysis. Okay, and then like I said, we also included some additional evaluations, including looking at spring groundwater levels, which is not, you know, has nothing to do with the sustainable management criteria, but also serves as a really important tool for us to you know, evaluate overall groundwater level conditions for the sub basin. And so here I looked at a few different periods of change. So I looked at spring groundwater level conditions over one year by looking at wells that were measured in 2026 and 2025 and comparing those. That's in that left pie chart there. The middle one, I did the same thing with a four year change, 2023 to 2026, and then again for a 10 year change, 2016 to 2025. And the reason the years kind of jump around a little bit is we were trying to pick kind of like end years that had similar precipitation conditions, similar water year types. And so again, red is bad, green is good. At first glance, we see that the yellow and orange stick out. That yellow represents very little change, less than two feet, whereas the orange is about a moderate decrease of two to 10 feet between those two years. One thing that I noticed at first glance is that, especially between the four-year and the one-year change, pretty similar conditions, which, I don't know, I guess, first off, indicates that things aren't worsening necessarily. But then, one sec. Looking at the 10-year change, you'll see that no significant change, the less than two-year difference is almost half. So that kind of indicates some stability in the long term. in line with the fall groundwater level assessment if you if you look at the Northeast Napa management area, I don't have charts for that but the the Northeast Napa management area average changes were larger in magnitude and more negative than outside of the Northeast Napa management area in all three So for example, the 2016 to 2025, that 10-year change, the Northeast Napa management area average or median change was negative 14 feet. So it was 14 feet. The groundwater elevation was 14 feet lower in 2025 compared to 2016. However, for the bulk of the Napa Valley subbasin, it almost didn't change. Positive 0.3 feet was the median for that. Overall, I would say that there's some relative stability. But of course, that Northeast NEPA management area warrants some additional assessments. And our second of six sustainability indicators is the reduction of groundwater storage, which you'll hear more about later, of course. There's two main approaches to evaluating groundwater storage. One uses spring groundwater levels, and the other one uses a model-derived estimate. So for the spring to spring groundwater level method, we take the monitoring network wells, which you can see on the map there, which is basically a subset of the groundwater level network. The ones in green on the map were used in the recent calculations, 2024 to 2025 and 2025 to 2026. The model-derived method is notably different in that it compares, it's more of a fall-to-fall difference because it's based on water year, and because of that, it's just naturally going to be a different value, but they're both different. estimates of groundwater storage change annual groundwater storage change for the the sustainable management criteria are based on the the model derived version so it's the the net groundwater extraction exceeding the sustainable yield for the sub basin but I won't explain too much about that since we're going to go into some refinements later on So I'll stick to the spring groundwater level approach. And so, like I said, we take wells in the network, we look at their spring groundwater levels in both years. So in this case, 2025 and 2026, we take those values and interpolate a groundwater surface elevation for each year. If you subtract those, you get the change in groundwater. elevation over the year period. And then if you multiply the aquifer storage coefficient, you can end up with an estimate of annual groundwater storage change in acre feet per year. And so on the map on the right is the spring 2025 to 2026 groundwater storage change estimated from groundwater levels. I added like a little cheat sheet to the legend there. So yellow is the most negative storage change that occurred and then the dark purple is the is actually positive but as you can see kind of at first glance an overwhelming part of the sub basin is those like Blues and so that's kind of like a more mild but still negative Storage change overall yeah so you'll see that there's kind of one piece of that yellow that like most negative storage change and that was in that kind of just between Yonkville and Napa. And then up in near Calistoga was that kind of more positive groundwater storage change. But overall, it was estimated to be about negative 4,800 acre feet. So we also look at the cumulative groundwater storage change using 1988 as a baseline. And this figure kind of shows the progression of things from 1988 all the way up to 2026. And you can see that there's just this general up, down, up, down, very much a function of precipitation and water year type. And I think the good part is that it seems to even itself out. It may jump around year to year, but the long-term trend is generally pretty stable with the cumulative storage change ending up at positive 360 acre feet. And our third sustainability indicator for the groundwater conditions is land subsidence. And for this one, it uses direct ground-based measurements at fixed benchmarks. It also uses NSAR-derived subsidence measured from vertical displacement data over time. And there's also a network of groundwater wells where measured groundwater levels in the fall, serve as a proxy for subsidence, and also help inform whether, like if we did see some subsidence, it could inform us whether groundwater pumping is linked to it in any way. So the minimum thresholds, we have that annual year-to-year rate of subsidence set at 0.2 feet per year of subsidence. We also have the new cumulative subsidence minimum threshold, which is 0.6 feet of subsidence over five years. Um, that was, um, like we mentioned earlier, uh, developed in response to one of those DWR recommended corrective actions. And then an undesirable result would occur if either of those were to be exceeded and groundwater extraction was determined to be the cause of it. However, it never got that far because evaluating conditions over the last five years, we see subsidence that is much lower than either of those minimum thresholds where the Maximum annual rate of land subsidence was less than 0.1 feet per year. And then the NSAR-derived total land displacement over 10 years was also very small. Negative 0.25 feet was the kind of like maximum. And again, that was over 10 years. The fourth sustainability indicator is groundwater quality degradation. There are three constituents monitored regularly as part of GSP implementation. That would be arsenic, nitrate, and TDS, or total dissolved solids. Groundwater quality in the subbasin is generally unproblematic, though there are elevated arsenic documented in the Calistoga area, thanks to some hydrothermal mixing. And then TDS can be high in the south, in that marshland area and in the tidally influenced regions close to the southern reach of the Napa River. So we have this network of wells. Again, the representative monitoring sites are in pink on the map. And at those, we have a minimum threshold set for each constituent. And it's currently set at the drinking water standard for California. And with that, over the evaluation period, we do see pretty consistent minimum threshold exceedances of arsenic and TDS. Nitrate is pretty awesome. It's zero. Not zero nitrate, but 0% minimum threshold exceedances. So. However, the MT exceedances for arsenic and TDS over the evaluation period are not linked to groundwater management. They're kind of relegated to those areas of the subbasin that we already have historically documented elevated concentrations. And none of the concentrations were outside of those historical ranges. And then the next sustainability indicator is the depletion of interconnected surface water. So that involves kind of two sister networks. One is the groundwater well monitoring network, most of them close to the Napa River or along some tributaries. And then the other monitoring network uses stream gauges that collect stream stage and or discharge data, the discharge data in particular because it is then applied to the stream flow depletion estimates. There are minimum thresholds set for the groundwater level monitoring network, which are those historical low groundwater elevations in the fall. And then there's also a minimum threshold for stream flow depletion, which, again, I won't really get into right now, because we're going to present some refinements for that as well. And then for the groundwater level network for interconnected surface water, Doing the same thing we did before, looking at the fall water levels at those representative wells, comparing them to the set minimum threshold and measurable objective, we see that there were some MT exceedances in 2022, but that was it. So no three years in a row, no undesirable results. And in fact, we do have quite a few monitoring wells that did have recorded fall measurements either close to or above the measurable objective, which is good. And then lastly, this is the last sustainability indicator, is seawater intrusion. Conditions for seawater intrusion are evaluated using a monitoring network of groundwater wells in the southern portion of the subbasin, as well as in the Napa-Sonoma lowland subbasin, which lies between Napa Valley and the San Pablo Bay. Chloride concentrations are measured at these network wells to provide the context for evaluating seawater intrusion. The minimum threshold is currently set the drinking water standard once again. Over the evaluation period, there have been MT exceedances. As you'll see on the map, the MT exceedances are in red, and then the other colors are, it's kind of like before, green is good, red is bad. And in fact, most of the chloride concentrations measured in this kind of seawater intrusion study area are pretty low, with the exception of in that kind of really tight, close to the tidally influenced Napa River area. We need more data, though, to fully come up with a comprehensive analysis of seawater intrusion. And I'll get into that a little bit more with the monitoring network assessments. But one proposed idea is to include bromide as a monitored constituent at these wells. Because if you have chloride and bromide, you can pinpoint whether seawater is the source of the saline conditions versus conate groundwater. And so to summarize the overall status of the subbasin in terms of each sustainability indicator over the evaluation period, which are the last five years, Land subsidence, groundwater quality, and interconnected surface water in terms of groundwater levels are in pretty decent shape. They show stability, not too much concern. Groundwater levels and groundwater storage in terms of spring groundwater levels are in fairly good condition there are some negative fluctuations particularly in the Northeast Napa management area so that does warrant a little bit of you know ongoing monitoring improvements and an analysis seawater intrusions kind of um a little bit up in the air. It's not really known to be an issue. But as part of this periodic evaluation, we're working on improving the monitoring network and monitoring ability to be able to evaluate it more thoroughly. And then the reduction in groundwater storage as defined by sustainable management criteria and also the interconnected surface water in terms of stream flow depletion have experienced undesirable results in the last five years and have thus prompted the refinements discussed in the periodic evaluation. And that will be previewed for you shortly here.

Thank you. Questions, comments from the TAG? And we will open up comments from the public after we come back from the break and we finish the second half. So once we wrap up this conversation, we will come back and open up for public comment. But right now, any comments from the TAG or questions?

I just had a question about the removal of the drought year exception. Was that statewide?

I believe it probably was. I think DWR was moving to not have that be a criterion that was part of it. And so it was included in other sustainability indicator, sustainable management criteria too. And I believe that's the case.

Yeah.

Couple really minor things with the nitrate Zero exceedances that looks to me like they set the nitrate level What sort the threshold high enough for or Generous enough so that everything in the San Joaquin Valley wasn't exceeding. I mean, you know what I mean that I'm I don't know what it is, but I would guess

Well, they were doing California water standards, right?

Correct.

Yeah. Statewide? Yeah. OK.

Correct.

All right.

So drinking water standards. Corrected. Yeah. All right. The Northeast Napa is always this outlier. And I think David Graves has suggested in the past that we not focus so much on that, because it's kind of its own thing, not very representative of the whole basin. And this is a bigger conversation than reviewing your report now. I just want to throw that out there, because once again, the Northeast Napa section is going off on its own, doing its own thing. And it's a bit distracting from what are the real problems, I think.

I would just say that's why it has its own name. We do talk about it differently for that reason.

Is this periodic evaluation a point in time where some type of change could be made to suggest separating that data or

So very good points, because they lead into this afternoon's discussion after the break. It's not an area that we can cleave off and completely treat independently, but we can refocus the view of what's occurring within the main Napa Valley floor and the Northeast Napa management area. And it involves some of the refinements that we're trying to make to the sustainable management criteria. However, it also brings to light, and you'll see it in slides later, that it does require more management because of groundwater use in that area and the inability of that area to support the amount of groundwater development that has occurred in that area. So we just need to make sure that we're, like, focused on which information is telling us what and what does that mean specifically to that area versus the basin on the whole.

And the purple pipes that go out to the MSD do not reach that area, or they do, or park?

I don't think so.

So that could be something that could be up for future discussion. It could. If there's more purple water available.

Yeah. If there was more ability to expand that, recycled water is one of the projects in management action. So to the extent that that could be an alternative source of supply, that would be very helpful.

Yeah, that's what I figured is that they didn't probably. But it could be helpful for us if we are going to have a discussion about that northeast management area in particular to have some maps of where the extent of where the reclave water is available and then where it's not in relation to sort of usage or wells or whatever within that management area.

Good suggestion. In past presentations related to the MST, where we've seen some stabilization in groundwater levels and then overlaying the locations of the recycled water delivery, that there seems to be a correlation in the improvement over time. But it took a long time to actually see that change.

Right, because there's not that much recharge, right, because of the geology of the area. But still, I mean, and I feel like the experience that we do have or the data that we do have for the MST then informs our strategy or our advocacy for, you know, reclaimed water in that area as a way to relieve some of the pressure on the groundwater pumping, right?

Yeah, that's a great idea.

Anything else?

I guess also with that, it would be good to get in. I don't really have an idea of or a very good understanding of sort of what the remaining availability of reclaimed water might be with, you know, and how that might relate to demand within that area as well.

Yeah. I'm just looking it up on our GIS, and the pipeline is a long way from northeast Napa. It doesn't even get all the way to Monticello and northeast Napa, so to Canaan Road.

I do think the city of Napa does distribute water up towards the country club and the developments up there, but you know.

It might be a nice one of these meetings to get a presentation from Napa SAN on, you know, what they currently do, what the projections are for the future.

It would also be nice to hear from any farmers already using recycled water where it's available just to hear their perspective.

I do. No issues really on our end materially. Some vineyards approaching like 15 years. Yauntville, Napa Sandwater in Los Carneros, and in Sonoma County with a few different districts.

I mean, to the point of sort of Carneros, right, and the salinity discussion is that that's the place where you do have salinity issues, you know, and your vines are pretty good indicators of that, and so having that reclaimed water is, not only does that provide a water source, but then it also provides a water source that's very, much better for vine health than some of the groundwater in that area.

Yeah, I think this was a great idea to explore. You know, it might take a big upfront investment to get a pipe up there, but yeah, in the long run, it could be a good thing.

I mean, that was a fairly large investment to get it out into the MST, so, and then even into Carnouse, right? So that was, my memory of that is that was a community funded in some ways, but

No, it was individual parcel owners in Carneros at least.

And that's for Napa Sand, right? Because there's also a section connected to Sonoma water.

Yeah, there's a portion of Carneros, which is in Sonoma County, which has been served by the Sonoma Valley Recycled Water District for...

There's sections in Carneros that are still Napa County being served. It's like just the edge of it, but there's some Napa County parcels that receive Sonoma water. I don't know. I don't think it's much, but there's a couple, because they couldn't... The pipe didn't go that way. It didn't go that far from Napa Sun, but we might be getting attention here. Any other comments? Okay so why don't we take a 10 minute break and then when we come back we'll hear the second half from Vicky.

I think we weren't quite ready to take a break.

Well not yet. Am I missing something?

The original plan was to cover the monitoring network assessment and then do a break, but whatever the...

I might have gotten ahead. I was looking at the agenda here, but ask for me to pee.

Thank you.

Okay. All right. We'll continue the conversation, Vicky, if you may. Thank you.

Okay. So in this part of the presentation OK, so Erica is going to give you an overview of the assessment of the collection and monitoring networks that have been part of the GSP implementation.

All right, yeah, so we have a collection of monitoring networks developed in the GSP to collect the data required so that we can monitor those sustainability indicators in the short term, the seasonal, and the long term. And so on the left are the six sustainability indicators that I briefly kind of went over the groundwater conditions for. We have monitoring networks for those. And there are kind of like a few sort of supplemental Monitoring networks such as the GDE monitoring network and the surface water quality monitoring network that I won't be going over during this presentation, but they will be included in the assessments in the periodic evaluation itself so I'll just focus on the networks for which we have sustainability indicators, which would be the seven and Of them so one for each Sustainability indicator except for there's two for interconnected surface water. We have the groundwater Well network and then the stream gauge network So in these maps, we have the sites, some sites that were originally in the network, and then some sites that were added to the networks. And on this map, the representative sites are again in pink. And then the ones that are little plus sign symbols, the ones that aren't circles, are the additions to the networks. That'll be the same for all of these maps. The groundwater level monitoring network has grown pretty impressively, almost twice the size of the original network. Some of the wells that were added were in the Napa Sonoma lowlands down south, so not technically in the subbasin, but valuable to track conditions in adjacent areas. And then overall, the site density meets criteria. It's improved a lot from five years ago. But there are some areas where we could use a little bit of improved coverage, but overall improved from five years ago. then for the groundwater storage monitoring network it has also increased in size over the last five years and in doing so we have more sites that are representative of the groundwater conditions in the principal aquifer which is where we want to draw those spring groundwater levels from for the groundwater level based groundwater storage assessments The network does meet standards and has improved since the GSP, but we could always make further improvements, which will only make those calculations even more accurate and reliable. The land subsidence monitoring network has not changed much since the GSP, especially in terms of number of sites. There have been a few groundwater well swaps, so to speak. And again, those are used to detect land subsidence by proxy. So we've kind of improved in that we've swapped out some for others that had better monitoring frequency or better known well construction information, for example. The NSAR data covers most of the subbasin. The frequency is great. At most, it's every seven days the satellite flies over. So we have a really reliable and sufficient way to determine the rate and extent of subsidence. We're checking all the boxes there. The groundwater quality monitoring network has grown considerably also over the evaluation period. The groundwater conditions are generally within historical ranges and have not really exhibited any degradation or issues. And so the current monitoring frequency is deemed sufficient and the coverage is good. So that's kind of the summary of it. groundwater quality network. And then for interconnected surface water, there's the groundwater wells monitoring network. It's improved a lot over the past five years, thanks to the addition of the nine dual completion dedicated monitoring sites that were installed, stretching from the marshland area in the south all the way up to Calistoga in the north. These dedicated monitoring sites, which the shallow wells of those make up the representative sites, are equipped with transducers to collect data at six-hour intervals, which helps make the evaluations even more robust. Then we also have the stream stage and stream discharge monitoring network. This one is also increased in size similarly thanks to recently installed transducers measuring stage near those dedicated dual completion monitoring sites. And then we also have those newer CalSIP gauges as well. We do want to make some, sorry, Basically, going along with the refinements to sustainable management criteria relating to stream flow deflation, the network will likely continue to be adjusted and improved over the next evaluation cycle. And then lastly, the seawater intrusion monitoring network. It has not changed much in size over the last five years. Some sites previously designated as representative sites, so those that have the sustainable management criteria attributed to them. They haven't been monitored in recent years, so that kind of reduces the number of viable sites to properly assess seawater intrusion conditions, particularly within the subbasin. So over the next evaluation cycle, one of the targets is to seek to actively recruit seek to recruit actively monitored groundwater wells and in strategic locations in the area that you see on the map so that like southern portion of the sub basin and then and then just outside of it as well um yeah and that's so that wraps up the overview of the monitoring assessments which are described in much greater detail including the other supplemental monitoring sites in the periodic evaluation

Thank you. Any questions or comments from the tag?

Thank you.

Sorry, one second. Matt, you had something?

Well, just a comment. At least thinking about interconnected surface water groundwater monitoring network, I think the conditions are going to be so variable from site to site, it's hard to say when you have sufficient spatial coverage. It's kind of like drawing an arbitrary line. But anyway. We can't do everything, but just to put that in there.

Thank you.

So the next part of our presentation is turning to the refinement of some sustainable management criteria. So we've touched on some of the things that we've been identifying as through prior reporting for the annual report and then earlier. today this first one is focusing on the reduction in groundwater storage but before we get to that just kind of a review of one of the slides from the annual report summary for water year 2025 where we summed up you know what's occurred over a period of time from water year 2022 2025, and we had an undesirable result for depletion of interconnected surface water. This was at the Oak Knoll Gauge where we had exceeded the streamflow depletion volumes three times at that location, so tipping the trigger for the definition for undesirable result. and then the reduction in groundwater storage we've had exceedances at the minimum threshold actually every year for six out of seven years and so that has been an undesirable result and as part of the annual reporting we've sort of tempered that you know definition with the caveat that you know we don't think conditions are that bad but that's all like in the context of you know well what does this indicator, what are we trying to learn from it? And so we'll talk about how that also relates to the brief discussion earlier about the Northeast Napa Management Area. And one of the things that has occurred in both of these circumstances is how we're looking at certain criteria over certain times and what are other influencing factors. And so we've had some time to think about how refinements might provide us with more informative information as we're trying to understand what are the data we're receiving from the monitoring networks, how are we trying to evaluate that data, how does that relate to the criteria, and what does that tell us about the management or project needs, management actions needed to achieve the long-term sustainability goal. So Erica had a slide earlier on the definition for the reduction of groundwater storage. And here, the focus for what we're talking about now is the fact that the undesirable result definition currently focuses on the seven-year average of the annual net groundwater extraction And any exceedance of that average that exceeds the sustainable yield, then that leads to an undesirable result. So one of the things that we see in this collection of seven years is what occurred in a very dry period, very dry period back to back in 2020, 2021, and then a very atypical kind of precipitation pattern and water year. in 2022, and the estimated amount of groundwater extraction occurring during that period. So no matter how much we're trying to reduce pumping in more recent years, we have those values as part of the seven-year average. So even if we're trying to lower what we're doing, the end result gives us a number that may not necessarily be representative of what we're achieving and what that means in terms of the overall sub-basin condition at the time. So one of the things that we've tried to do is look at, well, if we keep our current definition, we have the third column from the left is the collection of each of the seven years and the straight up seven year average. But if we look at what this means, if we differentiate the amount of pumping for the non-northeast Napa management area from the portion of the northeast Napa management area, we see different total amounts of pumping in those two areas. One of the things that we touched on briefly, I believe it was in April, about the work being conducted in support of the water availability analysis update was the development of a sustainable yield portion for the Northeast Napa management area. So when we considered the sustainable yield proportion for the non-northeast Napa management area of 14,450, and then separately look at the proportion of the sustainable yield for the northeast Napa management area of 550, we see a very big difference in what's occurring year to year relative to the exceedance of the sustainable yield, with the Northeast Napa Management Area every single year being double or more of that portion of the sustainable yield. So another thing that we've touched on in past discussions is the nature of the Napa Valley Subbasin on the whole. And as a relatively small alluvial river basin and its responsiveness to our hydrologic conditions. So when we see these very dry back-to-back water years followed by the very atypical distribution and precipitation in 2022, we see a very sensitive basin reaction to those conditions. So it's a pretty quick response. So one of the things that we're not able to reflect in our straight up seven year average is how the basin is changing a little bit more in recent time. compared to when we just average it over that whole period. So we don't want to set aside long-term conditions. Those are really important. But we also want to be able to emphasize the effects of the more recent hydrologic conditions. So, we've looked at an approach that involves a temporal weighting factor, and this is shown in the schematic in the lower right-hand side of the chart slide, where we have weighting factors associated with each of the seven years with the greatest emphasis being placed on the more recent years. So this could mean in a wet year, if those were recent years, it would emphasize those more. If we had our 2020-21 years, it would emphasize those more. But we wanted to see, OK, is this useful in terms of how we can better assess what's going on relative to our sustainable management criteria? So we've taken this temporal weighting factor, which by taking all of those factors, they add up to a unit basis of one. And those temporally weighted values then add in total up to our average over that seven-year period, or a value over that seven-year period. So we've tried to differentiate what's going on in the non-northeast Napa management area separately from what's going on in the northeast Napa management area. And then here, we're summarizing all the results from what we've done. On the far left bar of the chart, we have our sustainable yield value for the subbasin, the midpoint of which is the 15,000 acre feet per year. And then we also have a light shaded area behind that bar at the top where it shows a range of 13,000 to 17,000 acre per year, which represents some of the uncertainty surrounding that estimate of the sustainable yield. And that's all described in the Grow More Sustainability plan. Then as we move to the right in that chart, we see the non-northeast Napa management area, The blue color bar being where we have our value when it's temporally weighted, which exceeds the proportion of the sustainable yield for that part of the sub-basin. And then we move further to the right, and we see how this relates, the temporally weighted value versus proportion of the sustainable yield for the Northeast Napa Management Area, which it's a small part of the overall sub-basin sustainable yield. But it's still showing that it's more than double the amount of what that proportion of the sustainable yield is. So that's significant in the effect on that area. And then we have the total of those two when we tried to step back, look at the sub-basin on the whole, and we had that temporally weighted result over the seven-year period for the entire sub-basin. And when we think about that in relation to where the bands are for uncertainty, we're slightly above what our sustainable yield is at the elevated end of the uncertainty band with a value of 17,108 acre feet. So when we think about all the conditions on the whole, interconnected surface water being a whole other challenge, but think about what Erica was just describing, how from 2016 to 2025, we saw long-term, pretty stable conditions. So as we look at the effect of the more recent years on the sub-basin, we see that we're still pushing over the top. So it still says there is a significant value in the implementation that is occurring. Even before the GSP went to DWR, there was the direction from the Groundwater Sustainability Plan Advisory Committee to proceed with projects and management actions, the development of the work plan, and to look ahead to the 10% reduction in groundwater pumping. because the sustainability goal for the subbasin is not only to maintain status quo, it is to protect and enhance. And that was especially a focus related to interconnected surface water and especially the beneficial uses and users of the interconnected surface water system. So it also supports Napa County GSA's taking on the philosophy of it's really important to think about conservation all the time. This is not the kind of thing to think about, well, it's wet this year. That's OK. I can do whatever. That's not the plan. The plan is to continue to mitigate, do what can be done all the time because the basin is so responsive to any conditions. And so it's better to kind of build that buffer with the replenishment of the water where it can occur. So that is a summary of where we're at with a different approach for the sustainability indicator of the groundwater storage reduction and the sustainable management criteria, particularly focused on what constitutes an undesirable result and how we're trying to refine sort of the perspective as we look at that.

I'm not really familiar with temporal weighting, but is the general thought that, oh, is the most current years get higher weight? Right.

Right. So if it was a very dry year and we estimated more than the sustainable yield is the amount of pumping that was occurring, like if we look back at 2021 and we had 20,000 or whatever acre feet of pumping because it was a very dry year, if that was really what was happening, then that would be the emphasis of the temporal weighting factor. Because if that kind of year were next year, then that would get the most emphasis. But it also doesn't allow what occurred at some point more back in time, longer ago, to be driving things equally to what has had a greater effect in more recent time of a lesser amount of pumping, somewhat cooler temperatures, normal below average, but not the very dry years that we were experiencing.

Yeah, it seems to me from the figures that we've been shown over the course of the last several years is that the longer view you look at, the more steady the draw is.

Right. So that's okay when you're looking at, you know, it's a fluctuation of response to when there's more precipitation and more natural recharge and less amount of pumping and we see dry years, wetter years, historically, we would experience those in kind of a cyclic manner. But one of the concerns is climate effects and changes and very uncertain climatic patterns and precipitation patterns and hotter, drier temperatures. and all of those things that also much more dramatically affect the interconnected surface water system. So it's really, you know, all of these sustainability indicators together that are an essential part of the definition of sustainable yield, that it's not just about pumping and it's not just about replenishment. It's about all of these sustainability indicators and achieving the criteria.

Just a couple of comments. First, I don't know that the climate predictions are uh good enough for our region to say that we are going to be hotter and drier necessarily in fact some of them say that we will have more rainfall it'll just be at different times we just had one of the most humid summers and so like i think most of the predictions are for more variability rather than necessary I mean yes temperatures rising but then also within that a lot more variability in everything so you know just sort of as part of that conversation yeah um I'm curious how all of this information that we have now gained on the dry farm vineyards would then be sort of incorporated into some of this and then also So as far as grapevines go, pumping, yes, is definitely going to be reduced in wet years because you have all that soil moisture. In fact, I was talking to someone last week who they did not irrigate at all. And so I'm still back in this where we're modeling pumping. And if you were to look at that model and look at that parcel, it wouldn't say zero applied water in the model. Well, it'd be interesting to see the discrepancy between that specific parcel where I know that they didn't put on any water, even though they have the capability to do so. versus, like, what the model is saying. So I still would, you know, it would be great when sort of actual pumping and irrigation data come in so that we can look at what potential error there might be or, you know, difference there is between actual data and our modeled pumping.

It would be very helpful, and that's one of the objectives of the certification program that Jameson mentioned at the beginning of the meeting and trying to relate what actual pumping is occurring in certain areas, not necessarily needing to know it down to the parcel or to the landowner. But to have some kind of gauge as to, well, how is this actually panning out? Because in the models, we're seeing it could be 0.1 acre feet per acre is the estimated value in certain areas, or 0.3. And there are some areas that are 0.75 acre feet per acre. So it would definitely help to be able to gauge that. But if the pumping is less, that also means the sustainable yield can be less. It doesn't necessarily mean that that less pumping is going to keep the sustainable yield the same, because we're trying to meet all of these sustainable management criteria for all the sustainability indicators. So it still ties into what's happening with the connection between groundwater levels and discharge to the stream system.

Right, and we don't have this. It's frustrating because we don't have the slides anymore. Wasn't there one that had all of the different criteria and where we have undesirable results? So as far as our sustainability indicators go, right, and that storage one, if I understand it, is driven by our pumping modeling.

the model estimate of groundwater pumping. But it's also relating it to the model estimate of sustainable yield. So if we were to find that the pumping is lower, then the sustainable yield may also be correspondingly lower because we're also trying to meet the criteria related to interconnected surface water, land subsidence, everything else, with interconnected surface water being the most critical one in the Napa Valley Subbasin.

Right, which is 50-50.

Well, and that's a whole other, the next part of this discussion. But there is, the way that SGMA regulations are, it really goes forward from 2015, and that's the beginning of SGMA implementation and GSP implementation. the protection and enhancement described in the sub-basin sustainability goal doesn't necessarily take it way back in time to when conditions were much better. So those are more under a category of public trust interests, which are somewhat related but very different from what's required under SGMA.

But I still look at this and I see More no's than yes's. Correct. Which in my mind is you know. Okay so we're not there yet but we're also not

fully you know we're not yeah right well and that i mean there's places where you know land is some persons on the g-spac that groundwater sustainability plan advisory committee would probably um have a comment about that question or a comment about the comment because the there is a difference between the reduction in groundwater storage is an annual minimum threshold and undesirable result. And the depletion of interconnected surface water on the volume basis is a three-year minimum threshold period. So you don't really have the same opportunity for saying that yes, yes, yes the same way, because it's over a three-year period before you have the definition of an undesirable result. So I think it comes down to a lot of what Christian was describing, that it's really important that we understand the ecological needs and the flow relationship to those needs and how does that relate to the sustainable management criteria that we're trying to develop. And so what we're going to talk about shortly is very much reframing the current definition for interconnected surface water streamflow depletion. But we are by no means at some firm definition. It's a reframing to another interim definition because there's a lot of work underway to better understand, you know, what is that depth and flow over the critical riffle? I mean, how does that relate to the timing of when there are flows in the system? So I've kind of gone off on a tangent. Yeah, kind of. Sorry, sorry.

And then I guess, you know, some of this comes for me from, like, a social science perspective, too. Yes. And that you also have to think about what does lead to changes in behavior and and so I Won't go into that but I just like to leave it at that that and then also it occurs to me that you know Not only did we learn more about dry farm, but you know to Peters point earlier that we also learned about alternative Water sources and then also so how that is, you know feeding into some of the modeling that we're doing exactly and

There is an important part of this definition of the minimum threshold, and then similarly as it relates to the undesirable result, where it's talking about the net groundwater extraction. Currently, it is the estimated extraction pumping from the model. But if there were intentional recharge efforts where there's a quantified amount of recharge occurring, that that can get computed along with that groundwater extraction to reduce the total groundwater extraction. So that's another way to change how this is being computed and looking at the most conservative way, because we're not counting in a quantitative way the amount of intentional recharge, if it's occurring, what that is and how much is it. So it would be extremely helpful to have those specific data from those who are implementing those kinds of practices to be able to take credit for those kinds of activities.

And we did incorporate or are incorporating 1,000 or so dry farm verified acres into the NVI standards.

Right. So that's part of the computation. And the simulation would be an update to the land use.

Well, the acres are still coming out.

Right. Right.

You had a point, Monica, sorry.

About the alternative, you know, if you have captured water as well and how that is going to get integrated. If those... I don't... I mean, Jameson mentioned that there were those conversations. I don't know where they went as far as, you know, actionable data.

If there was... actual data, those could be readily integrated in the model. The assumption right now is that there's drainage and it's getting discharged to the river system. So it's accounting for the drainage as an assumption only by assuming where there may be tile drains. But if there was more specific information that could actually be incorporated in the model, it could be readily part of the simulated information.

Going back to the prior slide and the reduction in groundwater storage. So that's a computed value, right, from the model?

So the reduction of groundwater storage is just the name of the sustainability indicator, and it is a computed value based on the amount of groundwater extraction and the net groundwater extraction if there were other activities occurring that could be quantified. And it's that seven-year average.

so it's all based on this particular criterion is all based on modeled information and I'm wondering if you so if we have each year a reduction in groundwater storage wouldn't that imply that the water table is systematically dropping over time can we compare you know so

We did have that in certain years, and then we had some recovery. And what we see now with where this total when we temporarily weighed it, it's a better reflection of how near we are to that upper band of the sustainable yield estimate at the high end of the uncertainty so it says we're about in balance it doesn't say we're achieving our sustainability goal but it says we're about in balance based on the sustainable yield and so that is a good correlation to what erica described about over that long period of time we had dry years and we had water level declines and then we had wetter years and we have response the average over that seven years doesn't respond as quickly mathematically as our water levels do when we experience wetter years.

So I'm curious if we looked at some of the wells and see if they are systematically going down, which I don't think is the case, right? They're just seasonally. They're going back up in the wet season and then back down in the dry season, just more or less from year to year.

Correct for the Napa Valley floor, non-northeast Napa management area. Not the same in the northeast Napa management area, except the newer dedicated marring wells are near to the water table. And so those are differently responding than what's occurring with those that are completed in the more consolidated formation.

That was one of the slides that Erica pointed out, right?

looking at elevation right it was like minus 14 something feet compared to 0.3 feet over the whole sub basin over that 10-year period

I guess I'm kind of interested to put you on the spot. I don't know if you guys have looked at it, but seeing if the ISWL at Petra has trended also downward since we've installed it, water levels. It's been a couple of years, I know.

Surprisingly, I don't have that data.

Surprisingly, I don't have that data in my head exactly, but I don't think it's gone down, no. I don't think any of them have gone down.

Anything else from the tag? And then you have more material, right, Vicki?

Yes. Let's do that. In this one, we're turning to the refinement of the sustainable management criteria for interconnected surface water. And the first few slides are just a bit of a recap. So we have our two sustainability, the sustainable management criteria approaches, one being through water levels that Erica had described, and the other is looking at stream flow depletion volumes over the June to October period at the Pope Street Gauge and the Oak Knoll Gauge. And what we talked about when we summed up results for the Water Year 2025 report, this was a slide that we used to show what was occurring at Oak Knoll, where we had an increase in the amount of seasonal streamflow depletion between June to October. But at the same time, we were seeing more streamflow in the system during July and August and September compared to when we look back at 2024. And so one of the things that we're seeing is we have more depletion that we're computing, but we also have more measured streamflow during the summer fall period. And it's not just the modeled stream flow. We also have all of the gauge record. So one of the things that we also mentioned then at the time of the annual report summary is that the GSP regulations focus on the rate or volume of depletions that are caused by groundwater use and result in adverse impacts on beneficial uses that may lead to undesirable results. So this is a really important connection to why in the GSP, and then later in the interconnected surface water and grower independent ecosystems work plan. We had a plan to incorporate the California Environmental Flows Framework, and that's a major focus of the work plan. And everything that Christian was describing today and previously, about the importance of looking at what are the actual flows in the system, what effects is depletion having on the functional flows that are needed to support groundwater-dependent ecosystems. So this was a particular heavy emphasis then and now in the periodic evaluation. And as Christian mentioned, there's more that we're beginning to know, but then there's also more that would be needed to know in order to have a balance between the needs that are desired within the surface water system itself and then other beneficial users too. So in order to do this, we have a lot of things that we're trying to use or need to use to characterize the system, including the streamflow depletion, how much of it is being depleted from groundwater use, and we're simulating that. We have the streamflow occurring without groundwater use. That's a simulation because we're hypothesizing what happens when we don't have any pumping. We have the streamflow occurring without depletion, also the same. We need to simulate it. What would this look like if there was no pumping? And the relationship between how much is being depleted and the streamflow that would have occurred without that depletion. So this is a key thing is, you know, what's the percentage of the streamflow depletion from these two estimates? Then, of course, it's really important that we know, observe streamflow, what's actually measured, not just simulated with a model. These low flows, it's particularly difficult to try to simulate the low flows in certain times. And then trying to assess what are the ecologic needs of the various aquatic and terrestrial GDEs during critical periods of their life stages. So the next several slides are graphs. And I'll just say there's a lot of this information that will be in the periodic evaluation. And we're trying to illustrate some examples here. So this is summary information. for Pope Street. And this is only showing example information for a period that has more normal precipitation years. And we're looking at two different periods. The 2005 to 2014 period was our base period in the Groundwater Sustainability Plan. And then we're looking on the right-hand side of the slide, the period from 2015 to 2025, so over a 10-year period. We're just looking at what happens when we do those simulations that I just mentioned. So we have in the blue bars, we're highlighting certain months that from our coordination with Christian and his team, we're thinking that it could be more helpful to sort of reframe our focus for the time being. This is just looking at reframing the interim sustainable management criteria from June to October, where we have a lot of other things going on and dry conditions later in the fall and or storm events later in the fall period. And it's really more important from what Stillwater Sciences has done with all their GDE surveys and what the RCD has done with its stream connectivity surveys is to look more closely at the May, June, and then as we go into the later months, then it becomes less critical, at least for this modeling kind of focus and stream depletion kind of focus. And I'm going to get to other slides where we're talking about the critical nature of measurements, not just the modeled information. So here we're looking at what happens with the stream flow during the May through July period when we had no pumping and what amount of depletion is there and what is the percentage of depletion during those particular months. So we see a greater amount of flow remaining in the system in May compared to June and especially compared to July when we look at the 2005 to 2014 period. And it's kind of similar when we look at the more recent years. We have the percentage of streamflow depletion increasing as we look at May to June to July. So one of the things that we're trying to do is, what can we set up for minimum threshold criteria that try to focus on, we need a fair amount of flow in the system in May. There are other kinds of water years that result in exceedances. With these particular criteria, we don't have any exceedances during our base period. But we do have exceedances during the period from 2015 to 2025. So these are tentative. The minimum thresholds. are there as a bookend, but our real focus is on trying to achieve measurable objectives. So this is very much trying to get our heads around something besides the total absolute streamflow depletion volume, because it turns out that's not particularly meaningful when we have these very high volume amounts that aren't really telling us what is this doing compared to the flow in the system in these times when it's particularly critical. So in this next slide, sure.

That column that says criteria 35, 75, 98, I'm

That is the... What does that mean? That's the tentative minimum threshold percentage streamflow depletion. I should have put a label on that. So it's looking at if those were our criteria about not to go below those numbers of the percentage depletion. In our base period, we're above that. But there are some water year types where that isn't the case. So we're looking here at the normal precipitation years only and the statistics only for the normal precipitation years. In the periodic evaluation, there will be many, many tables of different water year types and what we see. But in the next slide, we're showing how there are other exceedances when we look at other water year types. So if we take the same criteria, which are shown with the red horizontal lines, that's the minimum threshold with the 35%, the 75%, and the 98% for May, June, and July. And we see during May and June and July when we're having an exceedance compared to those criteria. All of this is really trying to create some other perspectives other than the bulk streamflow depletion volume.

Can we go back to Monica's question? Where did those percentages come up, the minimum thresholds? Where are they from?

Yeah, we're trying to look at from the limited data that Stillwater has been able to develop thus far about the amount of flow at certain times for steelhead and for yellow-legged frogs. That is trying to get into flows in the range. When there's a streamflow depletion, And when there's the no pumping scenario, what amount of water is left in the stream? So these are thresholds that we're trying not to exceed.

And is that percentage the percent reduction or the percent that remains? It looks like it's percent reduction.

It is the percent. It's the depletion over what would occur if there was no pumping, but it's what would remain in the stream system with that kind of percentage of depletion. if that makes sense. So if we were trying to keep 10 plus CFS in the system at a minimum, then that's what we're trying to look at. And what percentage is streamflow depletion? And these aren't I'd say magic numbers across the board because we're trying to look at something not too complicated because we don't have enough data to support anything too complicated. So right now, and what I described to internally in our team, these are interim tentative. So these are so qualified as to be looking at the Pope Street area and the Oak Knoll area in a specific month and trying to achieve you know, at least a flow of a certain amount where preferably we have a lot higher flow even as a result of the depletion. So these are the minimums that we're trying not to achieve. We're not trying to get to these minimums. We're trying to stay well above them and to achieve a measurable objective.

Just from an ecological point of view, I'm surprised that we would have 98% reduction would be the threshold for July. I would think of anything that would have the percentage much lower for that time, just because there's so little water left in the stream anyway that you're more likely to try it out with this high number, high percentage.

Yeah, so we're looking for something that's at least wet, is the understanding from our colleagues.

Yeah, in July, we're mostly worried about. People can't hear you. You can work on hearing loud.

Here, here you go. Oh, I was going to say. This is me. This is me.

In July, we're mostly worried about frogs because the temperatures are too hot for steelhead and frogs just, the tadpoles just need it to be wet. So it's just like the goal is to just keep wetted conditions. just so that it's not 100% depleted, so that there's just some water still. And July is a kind of uncertain period for us right now. We don't really, we've only got one site where we saw frogs in the main stem, and it was right at the confluence of Sulphur Creek. So it's just, we just want it wet in July, if we can, for as long as possible.

And then by August, there are no longer any tadpoles?

They're hopping. Yeah, the tadpoles are gone, yeah.

And again, we're not trying to go in the direction of achieving that threshold. We're trying to stay away from that threshold to get to the measurable objective. So this next slide was just showing all of the years during both of these periods and what's occurring with exceedances under different kinds of water year types in these three months. And this is at Pope Street. There is, on the right hand side of the slide, we kind of put a little call out there because there are no bars for June and July where we had no flow under that situation when we also had no pumping. So there was no depletion because there was no flow to begin with. So these next two, they're really just very similar. We also looked at Oak Knoll. So I think all of the questions and wonderings that you may have about, well, how does this work and why is this? As we're trying to describe, the main objective is to try to come up with a different way to look at what's occurring with the effect of groundwater use on stream flow during the critical periods and not to look at it as a total volume of depletion, but rather how much water is remaining in the system because of that depletion. So we're looking at it as the percentage of the streamflow depletion that's occurred and trying to change that to lesser numbers as we go forward.

And so that percent depletion column is the average for 2015 to 2025, and then the number of exceedances is the number of years within that 10-year period

so that it was exceeded say twice in may exceeded is yeah that those statistics are specific to the normal water years occurring within that period so it's not every year of that period it's the four or however many normal water years occurred within that period

Okay. But the percent depletion is the average for those however many number of water years? Correct.

Correct. And don't take the numbers like individually to look at the percentage because they're based on the water years behind that come up with those statistics. So like if you don't want to take a look at what is my depletion over my no pumping based on those specific numbers because they're already averages of other numbers.

So the 2015 to 2025 window might have six normal years within it. And so the percent depletion in, say, the green, you know, May 40.8 isn't going to equal 9.6 divided by 44.3 because that's showing you the full 10-year range, right?

It's each of the normal water years within that. So each is coming up with that statistics rather than trying to do the statistic based on those numbers after they're averaged. That doesn't work.

You know this will be hard to explain to like a normal reader and especially since you've got Decimal places as well, which implies a certain precision which Given that you're kind of you know, pulling this from this and this from this. Well, that's a good point Yeah, that's a good misleading.

Yeah, that's a good point. I It's hard when you're working with the low flows. I mean, it's not too useful to round to zero. And then another one of these where we're trying to show there are a number of exceedances. So this is pointing out that we have management that can be done to try and lessen the number of exceedances where that's even possible for the GSA to affect. Because on the very dry, back-to-back very dry years, followed by the 2022 atypical precipitation year, That is not only an effect of the flow in the system reduced from groundwater pumping, it's also a much lesser amount of natural recharges occurring. So the water table is lowering, and then the groundwater pumping can exacerbate that effect. But taking the pumping away in and of itself isn't necessarily going to resolve that problem. So when we're trying to bring this together, here's the interim and the tentative interim. So we're still also mulling this about amongst ourselves. So we would very much appreciate any thoughts, feedback, input. As I mentioned, this is probably an interim meeting. definition that we're trying to arrive at that just allows for a shift off of our other total streamflow depletion volume during that June to October period to give us a better indication of what we're trying to achieve. And it's more about where we're trying to go towards a measurable objective of a lesser amount of the percentage of streamflow depletion in the months of May and June. And at the same time, try and do whatever we can do to not go over the minimum thresholds. And that's something we're trying to avoid.

going back a little bit but in this case now looking at the 35% for me so May's when we expect to have a lot of water relatively so why can't we afford to deplete more than 35% in May what are we trying to protect there specifically in the hydrologic function and ecological process

that's a good question i would think that we're trying not to pump great volumes for probably other reasons and i think we're trying to set the bar so that other mechanisms that are important to the stream system aren't also disrupted so i think it's partly another question for christian or just in general i mean if we were looking at certain periods of may when we had much higher flows or a water year like 2022 where it was very low flows and so i think it would be very difficult for us to be varying that per you know that definition all the time if we And maybe that's possible, but it seemed like it'd be hard to track if we were trying to predict what's happening in the moment. And a slide that I'm about to get to, all of this is really after the fact, because the only way that we're able to suss out the streamflow depletion volume and the percentage is with the model. And so all of that computation happens after it's already occurred. And so the other thing that we're focusing on as we redefine these definitions This was actually a recommendation within the groundwater sustainability plan was to Have a look at what's it been occurring with the precipitation? If we come forward from the beginning of the water year in October, you know what's happened by December January, you know whether What's happened up to that point? We can't predict exactly what's going to happen into the future, but we might have a pretty good sense of how much are things being affected already and what else might we need to plan for as we look ahead. So this is more relying on the actual precipitation and what's occurred across the sub-basin. And looking at the value of doing additional outreach and increasing attention to projects and management actions, emphasizing all the time, kind of beating the drum about more water conservation, It's a good thing. Less groundwater use if you can do it. That's a really good thing if we have conditions that are looking very dry. And like I mentioned earlier, we would like to think that this is kind of going on all the time. But if we need to get it higher on people's radar during these periods, it's the time to do it. And then another thing that we were encouraging is that because the modeling occurs after the occurrence of these conditions, is to look more closely at the measured flow data And at least by March, probably before that, the data exists. And so we have real-time data. Those real-time data are valued. Those real-time data are going to be at more locations with other gauges that are in. We have stage data. We have discharge data. and there's other information that we can look at on a more routine basis. And again, try to couple that with more stakeholder outreach, increase attention to what's going on in the system. We can tell it's hot or dry or whatever it's doing, but just bringing attention to things that should be top of mind.

So...

This is just the last slide. We have the draft periodic evaluation that we're working on and planning to make available in October for public review and comment. And this includes the Stillwater appendix, so all of the SEF report. And I think a lot of the information that Christian presented, we're very much trying to integrate that with what we're trying to reframe these definitions with. It is challenging. I think we know of the LA River was another place that Christian mentioned to the team where they're looking at section C and trying to look at the flows that are necessary. This is, for the most part, not a typical part of a SGMA process. So we're ahead of the curve in terms of what we're trying to define to better understand what we're trying to achieve for beneficial uses with interconnected surface water. Tentatively, this would be going to the GSA December 8th for the final periodic evaluation after we receive comments, update information based on comments, feedback, and then being ahead of the time frame to submit it to DWR at least by January 31 next year.

Are we trending to early October 1st or October 31st for the?

Mid. The 19th is what we're shooting for.

Just trying to figure out how much time. Yeah. How many, what is the page count looking like?

You may want to focus. You can pick your priority. Yeah, there will be an executive summary. And there will definitely be key people. That's the reason we wanted to give you kind of a preview today. The things that we've presented are probably the things that we've found to be the most challenging. because we're trying to reimagine what had been the definitions, like literal, at the time of the GSP. And we're trying to improve upon those definitions in a way that they're more meaningful related to what we're trying to evaluate and how we're trying to improve conditions or maintain conditions so that the sub-basin achieves the sustainability goal, which is that protection and enhancement, so improving upon what things were at the point of that 2005 to 2014 period, not just status quo.

So the new stuff with the stream flow, I noticed that there was really no Do you have the minimum threshold stuff and then but then to then translate that to the undesired result it also it often has a time And so I didn't see that. Is that because you're not there yet? Or will we see that in this?

It'll definitely be in the periodic evaluation. And we haven't really talked about that as an internal discussion. The current definition is based on three years. Okay. And this as an interim new definition would likely change again in the next periodic evaluation cycle. So it would be something in my view, to work within as improved upon definitions. But a lot of it will depend on what's actually measured, what's actually coming out of the discussions moving into Section C and SAF, what additional recommendations that Christian mentioned about trying to establish the flow discharge relationships at the critical riffle. All of those things will help refine.

You know what's going on with these definitions now are very interim Okay, but yet when you did those calculations that you presented for us in the table It was only for normal water It was not for so then but then you would do just a standard three years.

So the one slide Wait the confusing spot. No I Actually, not that slide, that slide. So this is more the text description. So we have the measurable objective being what we're trying to achieve and staying away from the minimum threshold. What we're trying to set our sights on is more the measurable objective. And so this is more looking at those percentages stream depletion, a reduction in that percentage of stream depletion in May and June in normal to wetter years.

So it wouldn't be a three-year thing. It would be within the last five years if we've had normal to below average years.

So recognizing that there may be exceedances. I mean, so this is why there may be a three-year period over which the undesirable result is defined, but the minimum thresholds are getting tripped more often than that, if that's the case. But the measurable objective, this tentative, is applying to normal and wetter, primarily because there's so much else that's occurring that the GSA has no control over under a very dry year situation. So there could be all the conservation in the world that happens, and then we still have other conditions.

Yeah, I'm trying to think what's the ecological basis for it being OK to reduce the flow by 60% in June and only 20% in May. Is it still a frog thing?

It's trying to relate it to what we know from our base period, 2005 to 2014. and how things are changing between May to June under this period during which we define sustainable yield and we're wanting to protect and enhance. So we're trying to look at what was it then and how do we improve upon that condition, if that makes sense.

I would say for May, you do need more water in May. There's a lot more going on. You can still be at the tail end of the emergence of eggs in wetter years, probably. And you've got smolts going out through the basin. So they need more water to pass, and they need it in more places. So I think that, and you also still, in May, you can still have frogs that are part of, they've got an egg mass that's out there. They're not quite tadpole-ing around yet, and that requires a little more flow, too. So to me, May is more sensitive, and June is more bonus. May is a more crucial month, I think, ecologically.

I suppose April would more reliably have the higher flows anyway, right?

Yeah, and there's not, the pumping isn't having much of an effect.

Right, and there's no pressure on it in terms of pumping.

Thank you.

Thanks. That provides an ecological justification for...

We're trying to integrate from what we had seen and documented in the GSP the value of implementing CEF and then having that be a key part of the work plan to what Stillwater has been doing with the monitoring. And then, you know, recognizing now, kind of stepping back, you know, what kind of information has been developed, but what additional information we really need in order to take it to the next level.

Looks like we don't have any more comments from the tag. We'll open up if there are any comments from the audience. Just a friendly reminder, it's our comments. If you have specific questions, I mean, you have three minutes, but if you have specific questions, you can always email us by email.

Okay. I want to comment on, they are somewhat question base, but when you're talking about spring to spring recordings for groundwater levels, I was just curious if it's a certain date every year or is it depending on the rainfall or is it an average of the spring to spring? And I recall that there were anywhere from 6 to 11 percent of the readings showed that they were below average or in red. And I was wondering if those readings were from the same well monitors or did they vary throughout the subbasin? And then my last comment is as far as temporal weighted formulas, is this something that's a formula that's established or does an algorithm change it given the data as it moves forward in time as a weighted new information is generated?

Erica, maybe you can go ahead and address Peter's.

Yeah, so for the spring to spring groundwater level conditions, each of the three analysis periods, the one year, the four year, and the 10 year, all used slightly different subsets of wells. That was just based on the available wells in the subbasin that had data during the spring for both of those years. So that just naturally varied a little bit. Like we had 69 wells in the 25-26 analysis versus 45 wells for the 2016-2025 analysis. And then to the point of when in spring were the measurements taken, I used the... shallowest depth to water or the um the greatest the most the highest groundwater level elevation as the spring maximum for that and then that spring being defined as february march and april

Yeah, I mean, we collect samples in mid-March for the most part, but if they're ISWLs that have data loggers, you can pick when it's the highest. It's just mid-March is what DWR has recommended, so that's the date we do, the 125 or so. Okay.

Anybody else in the room?

Chris Malin. Okay. So I would like it if we could be informed of how long the public comment period is. I know it starts in October 8, and how long does that run? And will there be, well, that's a question. We'd like to know how long the public comment period is open. And we'd also like to know if there's going to be a response to comments. Because that's a learning curve for the public. And that's very helpful if we can get response to comments. then I'm confused as to whether DWR, the Department of Water Resources, it sounds like we're parsing out the northeast area from the total picture of what's going on. And I'm wondering if If that's what we're doing, that's a question, too. I would like to see the approach of the Napa sub basin taking in the whole sub basin and going from there instead of, oh, let's parcel out the northeast part. What about the MST? We know that that's in depletion, too, and it's been in depletion since 1950. And that is part of the MST is considered to be included in the Napa sub-basin. And so is the northeast portion. So if we... spend a lot of time like let's take it away over here and now let's look oh now we're looking good because we took all this away but they are connected hydrologically subsurface groundwater flow that's why they're included in the sub basin so they affect the sub basin so why aren't we just looking at that as a whole And are we on the trajectory to reach sustainability by, what is it, 2040 or 42? Are we on track? I would like to know, are we on track? What are we doing to be on track? Because in terms of groundwater sustainability, I think that we need every bit of that time to deplete groundwater, to reduce groundwater pumping in order to reach sustainability. And I just feel like we're just so deep in the data weeds that, you know, are we getting there? Thank you.

Thanks. You guys have any quick comments on the review?

Yes, the three-week review starting October 19th. Yeah. And we will do a response to public comment.

Thank you. Anybody else in their room, online?

I have three callers. David, you will have three minutes.

Thank you. I'm curious as to when we will see any results about the voluntary groundwater pumping initiative that is being conducted by, I believe, ERA is the name of the consultant. whether or not that's successful or not. I'm also curious as to the impact of any measures by self-supplied pumpers to reduce their pumping. Third point is I proposed kind of a thought experiment of what if you modeled, say, storing from either existing ground tile drains or potentially even diverting high flow surface events, 3,000 to 5,000 additional acre feet before April to therefore leave the falling limb of the hydrograph untouched. That seems to me to be an interesting thought experiment that may solve a whole lot of problems biologically and hydrologically. So I'll leave it at that. I can also, I was on the Napa Sanitation District Board for eight years. I retired two years ago. I'd be happy to provide some information about water chemistry, water amounts, financing, and bit of cultural effects of uh the recycled water from napa sanitation district if that's desirable for free i'll do that thank you very much thanks david paul you will have three minutes

I don't know if we can, if you're unmuted, we can't hear you in the room. Yet. Maybe if we leave him and go to the next caller.

Michelle?

Hi, Michelle Benvenuto, Wine Growers of Napa County. We appreciate you looking at ways to better assess and refine the models. We are still concerned with the sustainable yield and how that is being modeled. I mean, when we look at the reduction of groundwater storage exceeding the sustainable yield six to seven years, and yet how does that reconcile with our cumulative groundwater storage? I think it's still positive. I guess it's just there's a lot of data here that's not reconciling. And you're talking about better assessing things and looking at different models, but you haven't even talked about relooking at the sustainable yield and how that is being calculated. So thank you.

Paul?

Paul, you can always make public comments via e-mail and we can attach it to the legislature after in case you're having technical difficulties. We're wading through the Napa River somewhere up in Calistoga as we speak, assuming it's Paul Blake. Please email your comments to us, Paul.

We have no other callers.

Okay. With that, then we'll pass it along for future agenda items.

You're going to see this again. Honestly, yeah. We need to bring back the CERT program. We need to bring back the recharge feasibility. We're in greater detail and in advance of that have kind of a one pager. I don't know what else is on our agenda for next. Our next meeting would be in November. Yeah. Yeah. That's it.

Yeah, we had the discussion in the reclaimed water for some point in the future too, right?

Thank you.

All right. Thank you everybody.

Meeting adjourned.

Meeting adjourned.